Chrome Version: 54.0.2832.0 (Official Build) (64-bit) Revision 6c7eba987dc174e1522212efec1676619aa26a5a-refs/heads/master@{#412743} 32/64 Bit.
OS: Mac (10.10.5)(10.11.5), Windows (7,8,8.1,10), Linux(14.04 LTS)

Steps:

1. Launch chrome and navigate to chrome://md-settings.
2. Keep focus on toolbar menu icon and press 'Enter' key.
3. Now, press 'Tab' key from keyboard and observe the focus.

Actual: Focus doesn't traverse to side nav bar.

Expected: Focus should traverse through side nav bar.

This is a regression issue, broken in M-50.

Manual Regression Range:
Good build: 50.0.2641.0
Bad build: 50.0.2643.0 

Narrow bisect:
https://chromium.googlesource.com/chromium/src/+log/7cadea4c77674b8f2c4b8842877de2d5d8d5670f..1784be25c32a243547048a8f426253dd12262529?pretty=fuller&n=100

Suspecting: r373893